Educational Codeforces Round 8 C. Bear and String Distance（贪心）

题意:

给定N≤105的字符串,定义字符距离dist(a,b)=abs(a−b)

求一个同样长度的但是距离总和为K≤106的字符串

分析:

按照距离大小排序,然后贪心的从大到小搞就可以了

其实我想多了,不用排序直接搞就行了−−

代码:

//
//  Created by TaoSama on 2016-02-21
//  Copyright (c) 2016 TaoSama. All rights reserved.
//
#pragma comment(linker, "/STACK:1024000000,1024000000")
#include <algorithm>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <string>
#include <set>
#include <vector>

using namespace std;
#define pr(x) cout << #x << " = " << x << "  "
#define prln(x) cout << #x << " = " << x << endl
const int N = 1e5 + 10, INF = 0x3f3f3f3f, MOD = 1e9 + 7;

char s
, ans
;
int n, k, r
;

bool cmp(int x, int y) {
return max(abs('a' - s[x]), abs('z' - s[x])) <
max(abs('a' - s[y]), abs('z' - s[y]));
}

void solve(int i, int a, int d, int& leave) {
if(leave > a) {
leave -= a;
ans[i] = s[i];
} else {
if(d > 0) ans[i] = 'a' + leave;
else ans[i] = 'z' - leave;
leave = 0;

}
//  printf("%d: %c %c\n", i, s[i], ans[i]);
}

int main() {
#ifdef LOCAL
freopen("C:\\Users\\TaoSama\\Desktop\\in.txt", "r", stdin);
//  freopen("C:\\Users\\TaoSama\\Desktop\\out.txt","w",stdout);
#endif
ios_base::sync_with_stdio(0);

while(scanf("%d%d%s", &n, &k, s + 1) == 3) {
int dif = 0;
for(int i = 1; i <= n; ++i) dif += max(abs('a' - s[i]), abs('z' - s[i]));
if(dif < k) {puts("-1"); continue;}
int leave = dif - k;
for(int i = 1; i <= n; ++i) r[i] = i;
sort(r + 1, r + 1 + n, cmp);
memset(ans, 0, sizeof ans);
for(int i = n; i; --i) {
if(!leave) break;
int j = r[i];
int a = abs('a' - s[j]), z = abs('z' - s[j]);
if(a > z) solve(j, a, 1, leave);
else solve(j, z, -1, leave);
}
for(int i = 1; i <= n; ++i) {
if(ans[i]) putchar(ans[i]);
else putchar("az"[abs('a' - s[i]) < abs('z' - s[i])]);
}
puts("");
}
return 0;
}